The invention relates to a wind turbine blade of glass or carbon fibre reinforced plastics comprising a conventional inner lightning conductor cable.
Strokes of lightning involve extremely strong currents of the magnitude 10 to 200 kA within a very short period. The effect is very strong and can cause burstings because the air confined in the blade expands explosively. It is known to insert strong interlaced cables in the blade. Then a metal collector is provided at the tip of the blade, said metal collector being of a predetermined width and serving to capture the lightning as well as to prevent this location from being too strongly heated. Such a wind turbine blade is known from WO 96/07825.
Furthermore it is known to reinforce the blade by means of a carbon fibre coating. A copper web can optionally be applied onto the carbon fibre coating so as to protect said carbon fibre coating.
The object of the invention is to provide an improved wind turbine blade with a lightning conductor.
A wind turbine blade of the above type is according to the invention characterised in that the blade wall comprises oblong strips of carbon fibre-reinforced plastics and that the inner lightning conductor cable and the oblong strips at regular intervals are interconnected by means of conductors.
The oblong strips of carbon fibre-reinforced plastics improve the stiffness of the wing, and the risk of flash-overs between the inner lightning conductor cable and the electrically conducting oblong strips is reduced by the potential-equalising by the interconnections at regular intervals. Thus a suitably stiff, relatively cheap and lightning protected wind turbine blade is obtained.